1. Field of the Invention
The present invention relates generally to thermostatic valves and, more particularly, to thermostatic valves for controlling coolant flow in internal combustion engine blocks.
2. Description of the Related Art
To maintain a desirable temperature of an internal combustion engine block during operation of an engine, a thermostatic valve is used to control the flow of coolant from the engine block through a cooling system and back to the engine block. The thermostatic valve is typically designed to open when the temperature of the coolant in the engine block exceeds a critical temperature, such as 120.degree. F., so that the hot coolant flows to a radiator where the coolant is cooled and returned to the engine block via a coolant pump. The thermostatic valve typically can open to varying degrees to maintain the temperature of the engine in the desired temperature range.
When the engine is turned off, the engine block cools and, typically, the thermostatic valve closes and circulation through the radiator is stopped. If the coolant on the radiator side of the valve remains hot, pressure inside the radiator can increase to undesirable pressures.
Current thermostatic valves serve to control the coolant flow adequately; however, the structure of the valves create large pressure drops in the coolant flow as they disturb the normal flow of and cause friction in the flowing coolant. For example, even though the thermostatic valve of U.S. Pat. No. 3,207,436 has been designed with a valve head having a smooth contour on one side, the valve head has a 90.degree. corner, so that the coolant flowing past the valve head must turn 90.degree., which substantially disturbs the normal flow of the coolant, causing a large amount of pressure drop in the coolant flow.
It is, therefore, desirable to have available a thermostatic valve which causes a reduced level of pressure drop in the coolant flow relative to prior thermostatic valves. With a reduced level of pressure drop, a given coolant pump can provide an increased amount of coolant flow for improved cooling efficiency and/or a given coolant pump will have a longer service life since it does not have to work as hard as it does with prior thermostatic valves.
It is also desirable to have available a thermostatic valve which provides a small amount of "back flow" through the valve from the radiator to the engine block to relieve any build-up of pressure on the side of the radiator during shut-down of the engine. It would also be advantageous if the structure allowing the back flow was simple and inexpensive to provide on the valve.
It is, therefore, one object of the present invention to provide a thermostatic valve for controlling the coolant flow from an internal combustion engine block through a cooling system.
It is another object of the present invention to provide a thermostatic valve for controlling coolant flow in an internal combustion engine block which causes a reduced amount of pressure drop in the fluid flow relative to prior thermostatic valves.
It is yet another object of the present invention to provide a thermostatic valve for controlling coolant flow in an internal combustion engine block which has structure which allows back flow of the coolant through the valve from the radiator to the engine block, which structure is simple in design and inexpensive to include on the valve.